Embodiments of the present invention relate to systems and methods for detecting the presence, location, and/or identity of objects bearing radio frequency identification devices.
Radio frequency identification (RFID) devices have been used in systems for tracking persons, animals, and objects of a wide variety including for example airline baggage, inventory, and the mail. When a large number of objects to be tracked are located in a common area, it may be desirable to locate the object that is identified by the system. Conventional systems lack sufficient accuracy to report the distance from a reference point to the desired object.
Without the present invention, searches of wide areas for items that have been identified by radio frequency identification consume time and use labor ineffectively. Inventory management using RFID devices, if improved to include object position reporting, would find wider application and thereby help reduce overhead costs in a variety of security, manufacturing, husbandry, and materials handling environments.
A locator according to various aspects of the present invention includes a receiver and a processor. The receiver receives several signals, each signal having respective indicia of identification device presence within a respective communication pattern. The processor performs a method for determining whether a first identification device is located within a zone. The method includes the following steps performed in any order. A first step of determining, in response to receiver signals, a respective reliability of communication between the receiver and a plurality of identification devices. The plurality includes the first identification device and at least one second identification device. A first and a second communication pattern each respectively has a periphery such that communication with a provided identification device when located beyond the periphery is less reliable than communication with the provided identification device when located within the periphery. The first identification device is located within the periphery of the first pattern. Each second identification device is located beyond the periphery of the first pattern and within the periphery of the second pattern. And, the first pattern has a periphery substantially within the zone. A second step of comparing each respective reliability of communication to a respective threshold to identify validly present identification devices. And, a third step of determining that the first identification device is within the zone in accordance with whether the first identification device is validly present within the first pattern, the second identification device is validly present within the second pattern, and the second identification device is not validly present within the first pattern.
A method, according to various aspects of the present invention, for determining whether a first identification device is located within a zone, includes the following steps in any order. A first step of operating a portable locator within the zone to determine a respective reliability of communication between the locator and a plurality of identification devices, the plurality comprising the first identification device and at least one second identification device. The first identification device is located within a periphery of a first communication pattern. Each second identification device is located beyond the periphery of the first communication pattern and within the periphery of a second communication pattern. The first and the second communication pattern each respectively has a periphery such that communication with a provided identification device that is physically located beyond the periphery is less reliable than communication with a provided identification device that is physically located within the periphery. And, the first communication pattern has a periphery substantially within the zone. A second step of comparing reliability of communication with an identification device via a first communication pattern and reliability of communication with the identification device via a second communication pattern to provide a result of comparison. And, a third step of indicating, in response to the result of comparison, that operation via the first pattern is within the zone.
A locator, according to various aspects of the present invention, includes a receiver and a processor. The receiver provides a signal having indicia of identification device presence within a communication pattern. The processor performs a method for determining whether operation of a portable locator is within a zone. The method includes the following steps performed in any order. A first step of comparing reliability of communication with an identification device via a first communication pattern and reliability of communication with the identification device via a second communication pattern to provide a result of comparison. And, a second step of indicating, in response to the result of comparison, that operation via the first pattern is within the zone. The first and the second communication pattern each respectively has a periphery such that communication with a provided identification device that is physically located beyond the periphery is less reliable than communication with a provided identification device that is physically located within the periphery. The first communication pattern has a periphery substantially within the zone. And the identification device is located beyond the periphery of the first pattern and within the periphery of the second pattern.
A method, according to various aspects of the present invention, for determining whether operation of a portable locator is within a zone, includes the following steps performed in any order. A first step of comparing reliability of communication with an identification device via a first communication pattern and reliability of communication with the identification device via a second communication pattern to provide a result of comparison. And, a second step of indicating, in response to the result of comparison, that operation via the first pattern is within the zone. The first and the second communication pattern each respectively has a periphery such that communication with a provided identification device that is physically located beyond the periphery is less reliable than communication with a provided identification device that is physically located within the periphery. The first communication pattern has a periphery substantially within the zone. And, the identification device is located beyond the periphery of the first pattern and within the periphery of the second pattern.
A method, according to various aspects of the present invention, for preparing for zone-based communication, such communication using a portable locator, includes the following steps performed in any order for each zone. A first step of determining a respective set of locations comprising at least one location, each respective location for operating the locator within the zone. All points within the zone being on at least one respective line of sight from at least one location of the set of locations. And, a second step of determining a respective set of communication pattern pairs comprising at least one pattern pair. Each pair respectively comprises a first pattern and a second pattern. Each respective pattern, operative with the locator, has a periphery such that communication with a provided identification device that is physically located beyond the periphery is less reliable than communication with a provided identification device that is physically located within the periphery. And, each respective first pattern has a periphery substantially within the zone. And a third step for each pattern pair, of placing at least one identification device beyond the periphery of the first pattern and within the periphery of the second pattern.
By using two patterns, one within and one outside the zone, the boundary of the zone and hence the location of the responder may be more accurately determined. When the determination of presence within a pattern is based on measurements of reliability of communication, in contrast to using only a single detection event, zone boundaries may be defined in otherwise difficult communication environments. By locating at least one identification device, also herein called a responder or marker, outside the zone, it can be determined whether operation of a locator is at a designated operating location; and the location of a lost or misplaced object having an attached identification device is presently located within the zone.